RFC 3438 L2TP IANA Considerations December 20021.1 Terminology
The following terms are used here with the meanings defined in
BCP 26: "name space", "assigned value", "registration".
The following policies are used here with the meanings defined in
BCP 26: "Private Use", "First Come First Served", "Expert Review",
"Specification Required", "IETF Consensus", "Standards Action".
2. IANA Considerations
L2TP [RFC2661] defines a number of "magic" numbers to be maintained
by the IANA. This section updates the criteria to be used by the
IANA to assign additional numbers in each of these lists.
Each of the values identified in this document that require a
registration criteria update are currently maintained by IANA and
have a range of values from 0 to 65 535, of which a very small number
have been allocated (the maximum number allocated within any one
range is 46) [L2TP-IANA]. Given the nature of these values, it is
not expected that any will ever run into a resource allocation
problem if registration allocation requirements are relaxed from
their current state.
The recommended criteria changes for IANA registration are listed in
the following sections. In one case, the registration criteria is
currently defined as First Come First Served and should be made more
strict, others are defined as IETF Consensus and need to be relaxed.
The relaxation from IETF Consensus is motivated by specific cases in
which values that were never intended to be vendor-specific have had
to enter early field trials or be released in generally available
products with vendor-specific values while awaiting documents to be
formalized. In most cases, this results in products that have to
support both the vendor-specific value and IETF value indefinitely.
For registration requests where a Designated Expert should be
consulted, the responsible IESG Area Director should appoint the
Designated Expert.
For registration requests requiring Expert Review, the Designated
Expert should consult relevant WGs as appropriate (e.g., the l2tpext
WG at the time of this writing).
The basic guideline for the Expert Review process will be to approve
the assignment of a value only if there is a document being advanced
that clearly defines the values to be assigned, and there is active
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RFC 3438 L2TP IANA Considerations December 2002
implementation development (perhaps entering early field or
interoperability trails, requiring assigned values to proceed without
having to resort to a chosen vendor-specific method).
2.1 Control Message AVPs
IANA manages the "Control Message Attribute Value Pairs" [L2TP-IANA]
name space, of which 0 - 46 have been assigned. The criteria for
assignment was originally IETF Consensus. Further values should be
assigned upon Expert Review.
2.2 Message Type AVP Values
IANA manages the "Message Type AVP (Attribute Type 0) Values" [L2TP-
IANA] name space, of which 0 - 16 have been assigned. The criteria
for assignment was originally IETF Consensus. Further values should
be assigned upon Expert Review.
2.3 Result Code AVP Values
IANA maintains a list of "Result Code values for the StopCCN
message," "Result Code values for the CDN message," and "General
Error Codes" [L2TP-IANA]. The criteria for Error Code assignment was
originally First Come First Served, and the criteria for CDN and
StopCCN Result Codes were originally IETF Consensus. Further values
for all Result and Error codes should be assigned upon Expert Review.
2.4 Remaining Values
All criteria for L2TP values maintained by IANA and not mentioned
specifically in this document remain unchanged.
3. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Alvestrand, H. and T. Narten, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
G. and B. Palter, "Layer Two Tunneling Layer Two
Tunneling Protocol (L2TP)", RFC 2661, August 1999.
[L2TP-IANA] Internet Assigned Numbers Authority (IANA), "Layer Two
Tunneling Protocol 'L2TP' - RFC 2661",
http://www.iana.org/assignments/l2tp-parametersTownsley Best Current Practice [Page 3]

RFC 3438 L2TP IANA Considerations December 20024. Security Considerations
This focuses on IANA considerations, and does not have security
considerations.
5. Acknowledgements
Some of this text and much of the format of this document was taken
from an internet document on EAP IANA Considerations authored by
Bernard Aboba.
6. Author's Address
W. Mark Townsley
Cisco Systems
7025 Kit Creek Road
PO Box 14987
Research Triangle Park, NC 27709
EMail: mark@townsley.net
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RFC 3438 L2TP IANA Considerations December 20027. Full Copyright Statement
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